Hello Wit!
<%
var books
{
    for(book : books){
%>
${for.iter.index}.《${book.name}》 ￥${book.price}
<%
    }
}
{
    var func = function(a, b){
        return a + b + arguments[3]
    }
    echo func("a", "b", "c")
}
{
    var map = {
        books,
        1: 1,
        "key2": "value2",
        3: 2 + 1
    }
    map[5] = 2 + 3
    map.~put("6", 2*3)
    for(key, value : map){
        echo key + ":" +value + "\n"
    }
}
%>